Service disruption: git converter currently down

Warner Losh imp at bsdimp.com
Mon Sep 23 20:44:18 UTC 2019


On Mon, Sep 23, 2019, 10:38 PM Ulrich Spörlein <uspoerlein at gmail.com> wrote:

> Am Mo., 23. Sept. 2019 um 20:51 Uhr schrieb Shawn Webb
> <shawn.webb at hardenedbsd.org>:
> >
> > On Mon, Sep 23, 2019 at 08:42:10PM +0200, Ulrich Sp??rlein wrote:
> > > Am Mo., 23. Sept. 2019 um 20:34 Uhr schrieb Shawn Webb
> > > <shawn.webb at hardenedbsd.org>:
> > > >
> > > > Hey Ulrich,
> > > >
> > > > I appreciate your hard work in maintaining the git mirror. Work like
> > > > this can sometimes go unthanked. I want to take a moment to show
> > > > appreciation for you and the FreeBSD project in maintaining the git
> > > > mirror.
> > > >
> > > > I do have a few concerns with what was stated in your email. I've
> > > > written my concerns inline. I hope this discussion is a positive one,
> > > > wherein upstream and downstream can effectively come to a conclusion.
> > > >
> > > > On Mon, Sep 23, 2019 at 08:16:25PM +0200, Ulrich Sp??rlein wrote:
> > > > > Am Mo., 23. Sept. 2019 um 19:51 Uhr schrieb Sean Chittenden
> > > > > <sean at chittenden.org>:
> > > > > >>
> > > > > >> Please note however, that more "garbage" metadata escaped from
> SVN into
> > > > > >> github, meaning 3rd parties have a hard time re-running the
> conversion and
> > > > > >> making sure that it matches SVN down to the metadata (i.e.
> timestamps).
> > > > > >>
> > > > > >> Eventually, this will have to be re-rolled and a new "master"
> branch will
> > > > > >> be force-pushed into github. There's no timeline for this yet.
> > > > > >
> > > > > >
> > > > > > Wait, what?  Can you elaborate?
> > > > > >
> > > > > > Discussion of a force-push to github has occurred a few times
> and been explicitly ruled out because most of our corporate citizens use
> github to integrate changes from FreeBSD.  Rerolling master was universally
> rejected when we socialized wanting to do this due to the level of
> disruption this would cause.  The feedback was that this would be a
> high-cost, low-value operation.  In the tradeoffs of purity vs pragmatism,
> pragmatism wins every time (that is the FreeBSD way).
> > > > > >
> > > > > > -sc
> > > > >
> > > > >
> > > > > This is not just about pragmatism and the disruption it would
> cause is
> > > > > vastly overblown by people who don't seem to know much about the
> git
> > > > > storage model.
> > > > >
> > > > > There *is* garbage metadata in the published version on github,
> there
> > > > > *is* a disclaimer on https://wiki.freebsd.org/GitWorkflow since
> > > > > forever, and the cost of switching from 1 published branch to
> another
> > > > > is literally:
> > > > >
> > > > > - git diff origin/broken_master mybranch > mybranch.patch
> > > > > - git checkout -b fixed_branch origin/fixed_master
> > > > > - patch < mybranch.patch
> > > >
> > > > Such a workflow breaks historical accuracy. Instead of `git annotate`
> > > > showing the history properly, it's now based on an "epoch commit".
> > > > Sure such a commit brings the branch to a working condition, but at
> > > > the cost of history.
> > >
> > > Is there really that much value in having "git blame" work in that
> environment?
> > > My mental model is of short-lived branches that get upstreamed, so I'm
> biased
> > > towards this not being all that big of a problem (for some at least).
> > >
> > > > >
> > > > > It should also be possible to merge both broken and fixed master
> into
> > > > > your branch (at the exact same SVN revision in time) and then you
> can
> > > > > follow fixed_master going forward. You'll schlepp around double the
> > > > > commit history, but not tree objects.
> > > > > If you want to retain history, you can upstream the changes prior
> to
> > > > > the switch
> > > >
> > > > I so wish that were possible for certain downstream projects. We're
> > > > unable to upstream the majority of our work. To argue "upstream your
> > > > work and you won't be affected" is to choose an argument that does
> not
> > > > reflect the reality of a growing portion of FreeBSD's downstream
> > > > consumers: the inability to work effectively with upstream.
> > >
> > > :/
> > >
> > > I'm 80% sure that you can just merge both branches and things will be
> fine
> > > (though the exact incantation will surely be black magic). I'd love to
> > > try this on
> > > an actual repo though, I don't have the time to craft some test repo
> to verify
> > > this assumption, and then find out that other repos are different).
> >
> > HardenedBSD's github repo has existed since 2013, with branches
> > stemming from that work existing still today. Perhaps HardenedBSD is
> > somewhat in a special case: we aim to provide the BSD community with a
> > clean-room reimplementation of publicly-documented parts of the
> > grsecurity patchset.
> >
> > With FreeBSD not taking the same approach, we will have very
> > long-lived branches. For example, our hardened/current/master branch
> > follows FreeBSD's HEAD and syncs every six hours. Meaning, we maintain
> > our patches, resolving whatever few merge conflicts arrive. The
> > hardened/current/master branch was created so many years ago, I've
> > forgotten when it was actually created (perhaps in 2013?)
> >
> > Though HardenedBSD's cause for existence may be a special case, this
> > problem can be viewed in a general fashion. I'm confident HardenedBSD
> > is not alone in facing issues of these types.
> >
> > Thanks,
>
> What I don't understand is how a security focused project can trust a
> random source for the svn2git conversion. I could have planted a bunch
> of backdoors and then come up with some SVN metadata corruption
> conspiracy as to why the commit hashes are different. Why would you
> trust me
>

The metadata has been independently audited. otherwise I'd be worried...

Git use has taken off to such an extent we'd need a well tested easy button
to do migrations that has good messaging and clear, easy to follow
instructions that are as automated as possible.

Warner

HardenedBSD of all people should be running the converter themselves
> and check that the content really matches what is in SVN (which it
> currently doesn't for metadata).
>
> Cheers,
> Uli
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